UNITED NATIONS, July 16 (Reuters) - Sudan’s president, accused of masterminding genocide in Darfur, might escape war crimes charges if he brings to justice two men suspected of mass killings, Western envoys said on Wednesday.

The International Criminal Court’s chief prosecutor, Luis Moreno-Ocampo, asked the ICC on Monday to issue an arrest warrant for President Omar Hassan al-Bashir on suspicion of crimes against humanity.

Moreno-Ocampo accused Bashir of a campaign of genocide that killed 35,000 people outright, at least another 100,000 through a "slow death" and forced 2.5 million to flee their homes in Sudan’s western Darfur region.

Sudan, China and South Africa have expressed concern that a formal indictment of Bashir could damage the stalled peace process aimed at ending the 5-year-old conflict in Darfur.

"The search for justice should not jeopardize the other priorities in Sudan," South Africa’s U.N. Ambassador Dumisani Kumalo told reporters ahead of a Security Council meeting.

U.N. peacekeeping officials and national diplomats say privately they fear an arrest warrant against Bashir could provoke a wave of violence against the joint U.N.-African Union peacekeeping force (UNAMID) or even prompt Khartoum to order all international peacekeepers in Sudan out of the country.

There are around 9,500 UNAMID troops and police in Darfur and another 10,000 U.N. peacekeepers in other parts of Sudan.

Sudan’s U.N. envoy Abdalmahmoud Abdalhaleem said he was in talks with the Russians and Chinese to find a way for the Security Council to use its power to freeze any ICC moves.

Western diplomats say it is too early to discuss a council suspension of any ICC indictment but added that Moreno-Ocampo made it clear a messy situation can be avoided if Khartoum were to change its behavior on earlier ICC charges.

They say Bashir could escape indictment if he ended what they see as impunity for two men the ICC charged last year over Darfur. Khartoum has not handed them to the court or started legal proceedings in Sudan to investigate the allegations.

ICC judges are not expected to issue a ruling on Moreno-Ocampo’s recommendation until October or November.

‘NO IMPUNITY’

One senior diplomat said on condition of anonymity that Moreno-Ocampo’s "mounting frustration was because of a complete lack of engagement or any response to the indictments."

The main allegation against Bashir was one of "command responsibility," he said.

"His refusal to cooperate in bringing to justice those that the ICC thought were responsible for the actual killings on the ground adds force, adds evidence to the allegation of command responsibility for those killings," the diplomat said.

"Now, were the situation to change, the prosecutor’s attitude might change." Other envoys confirmed this view.

French Ambassador Jean-Maurice Ripert and British Ambassador John both said it was "not too late" for the Sudanese authorities to cooperate with the ICC over the indictment of Humanitarian Affairs Minister Ahmed Haroun and former Janjaweed militia commander Ali Kushayb.

But Ripert, Sawers and other diplomats said they have no intention of interfering with the ICC process, which is independent and should be free of political pressure.

The U.S. special envoy for Sudan, Richard Williamson, told Reuters "there can be no impunity" for crimes in Darfur.

Bashir and his U.N. envoy Abdalhaleem say that Khartoum has no intention of cooperating with the ICC because Sudan, like the United States and Russia, is not a party to the court.

Human Rights Watch international law expert Richard Dicker said he strongly disapproved of the idea that Bashir should be allowed to negotiate his way out of an indictment.

"The pattern of crimes in Darfur does indicate responsibility at the highest level of Sudan’s government," he said. "It’s not an auction on eBay."

COUNCIL CONDEMNS ATTACK

The Security Council unanimously condemned an attack last week against UNAMID, in which well-organized militia men killed seven peacekeepers and wounded more than 20, calling it an "unacceptable act of violence."

One U.N. official said on condition of anonymity that the attackers used sophisticated weaponry not yet seen in Darfur, including recoilless rifles, which are lightweight weapons that can fire heavier projectiles than normal light arms.

Several diplomats said they suspected the attackers were linked to the Sudanese government but Abdalhaleem denied it.

Britain circulated a draft resolution among the 15 council members that would extend UNAMID’s mandate for another 12 months once it expires on July 31. The council is expected to vote on the draft before the end of the month.

The draft also calls for the rapid and full deployment of UNAMID, which at 9,500 people in Sudan is well below its planned full strength of 26,000.

Western states blame Khartoum for the slow deployment, saying it has been blocking non-African forces and has insisted on picking their nationalities. Khartoum accuses the West of exaggerating the scale of the humanitarian crisis in Darfur. (Editing by John O’Callaghan)